1. Field of the Invention
This invention relates generally to electronic identification and recognition systems and more specifically to such systems wherein it is not necessary to make physical contact between the identifier section and the reader section.
2. Description of the Prior Art
There are various electronic identification and recognition systems known in the art wherein the identifying device is portable. The identifying device is hereinafter referred to as an identifier section and may take the form of a card, tag or key. The recognition station, hereinafter known as the reader section, is prepared to recognize certain predetermined characteristics of the identifier section when the identifier section is brought within the proximity of the reader section.
Uses for such systems may include identification of persons having identifier sections in their possession. For example, the identifier section may take the shape of a credit card and have an electronic circuit embedded therein for radiating signals of identifying intelligence. An individual possessing the card may position it adjacent a door that the individual desires to enter. A reader section is arranged to control the door latch and if it recognizes radiated signals of a certain predetermined intelligence, the reader section opens the door. Other uses for such systems include having the identifier section in the form of a tag attached to a vehicle to be identified. As the vehicle passes a certain location, such as a toll booth, its identification is recognized and recorded. Also, in production lines, garments or other items may carry identification sections as tags so that they can be appropriately processed as they are recognized along various points in the production process.
The prior art includes various patents and patent applications by the present inventor. The patents include U.S. Pat. No. 3,732,465 for "Electronic Sensing and Actuator System", issued May 8, 1973; U.S. Pat. No. 4,223,830 for "Identification System", issued Sept. 23, 1980; U.S. Pat. No. 4,236,068 for "Personal Identification and Signaling System", issued Nov. 25, 1980; U.S. Pat. No. 4,384,288 for "Portable Radio Frequency Emitting Identifier", issued May 17, 1983; U.S. Pat. No. 4,388,524 for "Electronic Identification and Recognition With Code Changeable Reactance", issued June 14, 1983; U.S. Pat. No. 4,459,474 for "Identification System With Separation and Direction Capability and Improved Noise Reduction", issued July 10, 1984; U.S. Pat. No. 4,473,825 for "Electronic Identification System With Power Input-Output Interlock and Increased Capabilities", issued Sept. 25, 1984; U.S. Pat. No. 4,546,241 for "Electronic Proximity Identification System", issued Oct. 8, 1985; U.S. Pat. No. 4,580,041 for "Electronic Proximity Identification System With Low Power Identifier, Simplified", issued Apr. 1, 1986; U.S. Pat. No. 4,600,829 for "Electronic Proximity Identification and Recognition System With Isolated Two-Way Coupling", issued July 15, 1986; U.S. Pat. No. 4,654,658 for "Identification System With Vector Phase Angle Detection", issued Mar. 31, 1987; U.S. Pat. No. 4,656,472 for "Proximity Identification System With Power Aided Identifier", issued Apr. 7, 1987; and U.S. Pat. No. 4,782,342 for "Proximity Identification System With Lateral Flux Paths", issued Nov. 1, 1988. In addition, there is currently pending U.S. patent application Ser. No. 07/203,944, now U.S. Pat. No. 4,888,474, for "Proximity Identification System With Lateral Flux Magnetic Rod Coupling", filed June 8, 1988.